For example, thrust roller bearings that support thrust loads are sometimes placed at such locations in automatic transmissions for automobiles, car air conditioner compressors, etc. that are subjected to thrust loads. For improved fuel efficiency and power saving, it is desired to reduce running torque of such thrust roller bearings. A thrust roller bearing includes bearing rings arranged in the direction of the rotation axis of the thrust roller bearing, a plurality of needle rollers that roll on raceway surfaces of the bearing rings, and a cage that retains the plurality of needle rollers. Some cages are manufactured by bending a steel sheet and then punching out pockets that accommodate the rollers.
A technique relating to the cages included in such thrust roller bearings is disclosed in, e.g., Japanese Unexamined Patent Publication No. H10-220482 (Patent Literature 1). The thrust roller bearing cage of Patent Literature 1 includes an annular body having concave and convex portions formed in the thickness direction, and projecting portions formed in a radially outer part of the annular body. The projecting portions are formed such that those parts of the radially outer end face of the folded part of the annular body which are located at the positions of the pockets project inward in the radial direction, and the tip ends of the projecting portions face approximately the centers of the end faces of the rollers. Patent Literature 1 discloses that this thrust roller bearing cage reduces running torque of the rollers as the tip ends of the projecting portions contact the rollers at positions near the rotation centers of the rollers.